Add some constant propagation tests

src/test/mir-opt/const-prop-1.rs

@@ -0,0 +1,59 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+fn main() {
+    let x = 10;
+    let y = 20;
+    if x == 12 {
+        [42u8][y];
+    } else {
+        return;
+    }
+}
+
+// END RUST SOURCE
+// START rustc.node4.CsPropagate.before.mir
+// bb0: {
+//     var0 = const 10i32;
+//     var1 = const 20usize;
+//     tmp1 = var0;
+//     tmp0 = Eq(tmp1, const 12i32);
+//     if(tmp0) -> [true: bb1, false: bb2];
+// }
+//
+// bb1: {
+//     tmp4 = [const 42u8];
+//     tmp5 = var1;
+//     tmp6 = Len(tmp4);
+//     tmp7 = Lt(tmp5, tmp6);
+//     assert(tmp7, "index out of bounds: the len is {} but the index is {}", tmp6, tmp5) -> bb3;
+// }
+//
+// bb2: {
+//     return = ();
+//     goto -> bb4;
+// }
+//
+// bb3: {
+//     tmp3 = tmp4[tmp5];
+//     tmp2 = tmp3;
+//     return = ();
+//     goto -> bb4;
+// }
+// END rustc.node4.CsPropagate.before.mir
+// START rustc.node4.DeadCode.after.mir
+// bb0: {
+//     goto -> bb1;
+// }
+//
+// bb1: {
+//     return = ();
+//     return;
+// }
+// END rustc.node4.DeadCode.after.mir

src/test/mir-opt/const-prop-2.rs

@@ -0,0 +1,45 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+fn main() {
+    let cfg = cfg!(never_ever_set);
+    let x = 42 + if cfg { 42 } else { 0 };
+    ::std::process::exit(x - 42);
+}
+
+// END RUST SOURCE
+// START rustc.node4.CsPropagate.before.mir
+// bb0: {
+//     var0 = const false;
+//     tmp1 = var0;
+//     if(tmp1) -> [true: bb1, false: bb2];
+// }
+//
+// bb1: {
+//     tmp0 = const 42i32;
+//     goto -> bb3;
+// }
+//
+// bb2: {
+//     tmp0 = const 0i32;
+//     goto -> bb3;
+// }
+//
+// bb3: {
+//     var1 = Add(const 42i32, tmp0);
+//     tmp4 = var1;
+//     tmp3 = Sub(tmp4, const 42i32);
+//     std::process::exit(tmp3);
+// }
+// END rustc.node4.CsPropagate.before.mir
+// START rustc.node4.DeadCode.after.mir
+// bb1: {
+//     std::process::exit(const 0i32);
+// }
+// END rustc.node4.DeadCode.after.mir

src/test/mir-opt/const-prop-loop-1.rs

@@ -0,0 +1,80 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+fn hdrty() -> usize { 6 }
+
+fn inc(idx: u16) -> usize { 1 }
+
+fn main() {
+    let hdrty = hdrty();
+    let max = match hdrty {
+        0 => 6,
+        1 => 2,
+        _ => 0,
+    };
+    let mut i = 0;
+    while i < max {
+        let next = inc(i as u16);
+        i = next;
+    }
+}
+
+// END RUST SOURCE
+// START rustc.node17.CsPropagate.before.mir
+// bb6: {
+//     tmp1 = var2;
+//     tmp2 = var1;
+//     tmp0 = Lt(tmp1, tmp2);
+//     if(tmp0) -> [true: bb8, false: bb7];
+// }
+//
+// bb7: {
+//     return = ();
+//     return;
+// }
+//
+// bb8: {
+//     tmp5 = var2;
+//     tmp4 = tmp5 as u16 (Misc);
+//     var3 = inc(tmp4) -> bb9;
+// }
+//
+// bb9: {
+//     tmp6 = var3;
+//     var2 = tmp6;
+//     tmp3 = ();
+//     goto -> bb6;
+// }
+// END rustc.node17.CsPropagate.before.mir
+// START rustc.node17.CsPropagate.after.mir
+// bb6: {
+//     tmp1 = var2;
+//     tmp2 = var1;
+//     tmp0 = Lt(tmp1, tmp2);
+//     if(tmp0) -> [true: bb8, false: bb7];
+// }
+//
+// bb7: {
+//     return = ();
+//     return;
+// }
+//
+// bb8: {
+//     tmp5 = var2;
+//     tmp4 = tmp5 as u16 (Misc);
+//     var3 = inc(tmp4) -> bb9;
+// }
+//
+// bb9: {
+//     tmp6 = var3;
+//     var2 = tmp6;
+//     tmp3 = ();
+//     goto -> bb6;
+// }
+// END rustc.node17.CsPropagate.after.mir